Exam Question

Question 1

Evidence for shells and sub shells

Answer 1

Atomic emission spectra:

Question 2

1st ionisation energy trend in group 1

Answer 2

As you go down the group ionisation energy DECREASES

Because:

-more shielding meaning less attractive forces between outer electron and the nucleus
-larger atomic radius meaning less attractive forces between outer electron and the nucleus
-a greater nuclear charge meaning more attractive however it’s insignificant

Question 3

1st Ionisation energy across a period

Answer 3

1st ionisation energy increases across the period

Because:
- atomic radius decreases meaning stronger attractive forces between the electron and the nucleus
- similar shielding meaning doesn’t effect at all
- a larger nuclear charge meaning more attractive forces between the electron and the nucleus (it’s insignificant)

Question 4

Alkanes in crude oil separated by fractional distillation

Answer 4

Alkanes have different carbon chain lengths.

Meaning different boiling points

Allowing for fractional distillation

Question 5

Two major reasons for cracking

Answer 5

• creates alkanes and alkanes
• alkanes smaller and more useful used doe fuels
• alkenes are used for smaller more useful polymers